The example embodiments relate to precision frequency clock signals generated from molecular rotational quantum response in a cell and, more particularly, to a system incorporating wave interrogation of the cell.
Precision clock signals, usable as a base frequency source either directly, or converted (e.g., divided down) to some multiple of a base frequency source, can be generated from various circuits and configurations. One precision clock signal example is an atomic clock, so named as its signal is produced in response to the natural and quantum response of atoms or molecules, to an excitation source. In one approach, such atoms are in the form of alkali metals stored in a chamber, where the excitation source can be one or more lasers directed to the cell and the response of the chamber atoms is detected by measuring the amount of laser energy (photons) that passes through the chamber as the laser frequency sweeps across a range. In another approach, such molecules are in the form of dipolar gases also stored in a chamber, where the excitation source is an electromagnetic wave propagating through the chamber and the response of the chamber atoms is detected by measuring the amount of electromagnetic energy that passes through the chamber as the energy source sweeps across a range.
Further to the above, an example of a millimeter wave atomic clock is described in U.S. Pat. No. 9,529,334 (“the '334 Patent”), issued Dec. 27, 2016, hereby incorporated fully herein by reference, and which is co-assigned to the same assignee as the present application. The '334 Patent illustrates, among various other things, an atomic clock apparatus including a sealed cavity storing a dipolar gas, with an electromagnetic entrance into which an electromagnetic wave (or field) enters near a first end of the cavity and an electromagnetic exit from which an electromagnetic wave exits near a second end of the cavity. The electromagnetic wave that so exits is measured to determine an amount of absorption by (or transmission through) the dipolar gas, with the measure indicative of the quantum response of the gas as a function of the wave frequency. The '334 Patent also discusses a selection of pressure for the cavity-sealed dipolar gas, noting that pressure reduction below a desired pressure would reduce the magnitude of the peak response transition, thereby degrading the ability to detect and track the quantum response of the dipolar gas.
While the prior art approaches described above can provide useful to quantum response detection, the present application provides alternatives to the prior art, as further detailed below.